1. Technical Field
The present invention relates to a dental implant and a method for manufacturing the dental implant.
2. Related Art
An implant (dental implant) has been extensively used to restore the function of a tooth lost by various causes. In general, the dental implant includes a fixture anchored to a jawbone and an abutment threadedly coupled to the fixture.
A crown restoration is capped on the dental implant (the abutment threadedly coupled to the fixture) and fixed thereto with dental cement, thereby bringing the dental implant into a shape corresponding to that of an original tooth.
Conventionally, from the standpoint of compatibility to a living body, strength and so forth, titanium or titanium alloy has been generally used as a constituent material of the implant (see, e.g., JP-A-2000-24004, page 3, right column, lines 40 to 42).
Ceramic is generally used as a constituent material of the crown restoration to lessen the difference in appearance between the crown restoration and the tooth of a living body.
A metal portion (metal layer) made of gold alloy or the like is arranged on the inner surface (the implant-side surface) of the crown restoration in an effort to improve occlusion or to reliably prevent occurrence of cracks in the crown restoration.
In other words, a laminated body including a metal portion (metal layer) made of metal and a layer made of ceramic is widely used as the crown restoration.
If the crown restoration has the metal portion as set forth above, however, a galvanic cell is formed between the metal portion and the titanium-made implant. This may possibly cause metal to be eluted into the living body, thereby adversely affecting the living body.
With a view to avoid such a problem, it would be conceivable that the metal portion of the crown restoration is fixed to the implant with a relatively large quantity of dental cement so that they should not make contact with each other.
In this case, it becomes difficult to adjust the height and angle of the crown restoration to be fixed to the implant as designed at the outset. It is also difficult to obtain sufficiently high bonding strength.
In order to prevent contact between the titanium or titanium alloy of which the implant is made and the metal portion of the crown restoration, it would also be conceivable that the titanium or titanium alloy is coated with insulating ceramic.
Ceramic is usually inferior in its bondability with titanium or titanium alloy, although it exhibits superior bondability with gold alloy. This makes it difficult to sufficiently increase the bonding strength between the portion made of titanium or titanium alloy and the portion made of ceramic.
As a result, mismatching (bumpy occlusion or the like) of the implant is apt to occur, consequently deteriorating the feeling of use of the implant.